Extracorporeal blood pumps are used to assist patient blood circulation in a variety of surgical procedures including both short and relatively longer-term procedures including cardiopulmonary bypass (CPB) Extracorporeal Membrane Oxygenation (ECMO) or Extracorporeal Life Support (ECLS). One type of blood pump commonly used is a magnetically driven centrifugal blood pump which includes an external drive motor that drives the blood pump via magnetic coupling between a drive motor magnet and a blood pump impeller magnet. Magnetic coupling in this manner allows for the centrifugal blood pump to be housed in a separate and disposable sealed unit and discarded after a single use while the pump drive may be reusable.
Magnetically driven centrifugal blood pumps may include one or more bearings. In some magnetically driven centrifugal blood pumps, a pump impeller is captured between an upper and a lower bearing and as the impeller spins or turns, the pressure distribution of the pumped fluid (e.g. blood) generates an upward or impeller lift force which acts on the upper bearing. Conversely, the magnetic attraction between the impeller magnet and the drive magnet results in a downward force which acts on the lower bearing. The net force on the bearings is the summation of these two forces. Over time, the forces acting on the bearings may result in a finite bearing life. Therefore, it would be advantageous to minimize forces acting on the bearings so as to extend bearing life. Extending the life of the blood pump bearings may advantageously allow for use of the blood pump in extended or longer term procedures or applications.